i) Field of the Invention
The present invention relates to an occlusion catheter for the ascending aorta used for obstructing the blood flow in the ascending aorta.
ii) Prior Art
When a cardiac surgery is performed, the blood flow in the ascending aorta is obstructed generally using a conventional cross-clamp through an opening in a patient""s chest formed by thoracotomy.
Recently, there have been attempts to obstruct the blood flow in the ascending aorta using an occlusion catheter for the ascending aorta (hereinafter referred to as xe2x80x9can occlusion catheterxe2x80x9d) inserted through a femoral artery, for example, without performing an open chest operation.
An occlusion catheter of this type comprises a tube and a balloon disposed on the circumference of the distal end of the tube. The tube is inserted through the femoral artery and advanced through the thoracic aorta to the ascending aorta, in which the distal end of the tube is placed and the balloon is inflated, with the result that the blood flow is obstructed.
In another occlusion catheter, a cardiac muscle protective drug supplied from the proximal end of the tube is delivered to the distal end of the tube and released from a drug release aperture provided at the distal end of the tube.
These conventional occlusion catheters, however, have the following problems: The conventional occlusion catheter to be inserted through the femoral artery may hinder the blood flow directed to the lower limb, particularly, of a patient whose blood vessel in the lower limb is thin. In such a case an occlusion catheter of this type cannot be used.
The conventional occlusion catheter requires a guide wire in order to push the occlusion catheter throughout a long path from the femoral artery to the ascending aorta. As a result, a lumen to pass the guide wire therethrough must be provided in the tube, which leads to a relatively large diameter of the catheter and therefore a further factor of hindrance to the blood flow.
Furthermore, since the conventional occlusion catheter is long enough to extend from the femoral artery to the ascending aorta, the flow path resistance of the lumen in the tube is so large that the flow rate of the cardiac muscle protective drug cannot be easily increased. Although the flow rate of the cardiac muscle protective drug can be increased by simply having a lumen of a larger inner diameter, such a lumen necessarily requires a catheter of a larger diameter, which may hinder the blood flow toward the lower limb.
When inserted through the femoral artery, the conventional occlusion catheter may have its balloon damaged in the case where the blood vessel in the lower limb or the aorta is calcified, or cannot be easily advanced through a meandering blood vessel.
While the tube preferably is flexible enough to curve to a certain extent for better operation in the blood vessel, the tube having an excessive flexibility cannot support the balloon which is pushed by the blood flow from a pump oxygenator or the infusion pressure of the cardiac muscle protective drug. In this case, the balloon together with the tube is to be displaced from the proper indwelling position. To avoid such displacement of the balloon, a substantially hard tube is generally employed and operationality in the blood vessel is necessarily sacrificed.
The conventional occlusion catheter has a structure wherein displacement of the catheter tube in the axial direction is easily conducted to the balloon. Specifically, when the proximal end of the catheter tube is displaced in the axial direction, the distal end of the catheter tube is also displaced in the axial direction, with the result that the balloon is displaced as well. Thus, it is not easy to retain the balloon in the proper indwelling position.
Wherefore, it is an object of the present invention to provide an occlusion catheter capable of obstructing the blood flow in the ascending aorta without inserting the same through the femoral artery.
Another object of the present invention is to provide an occlusion catheter capable of maintaining the condition where the balloon is placed in the proper indwelling position.
To solve the above-mentioned problems associated with the prior art occlusion catheters, the inventors of the present invention first considered inserting an occlusion catheter directly into the ascending aorta in the vicinity of the heart after opening the chest in order to obstruct the blood flow when a cardiac surgery is performed.
This reduces the possibility of preventing the blood flow toward the lower limbs, and facilitates an increase of the flow rate of the cardiac muscle protective drug. Also, calcification or meandering of the blood vessel in the lower limb or the aorta does not present problems.
However, the above prior art occlusion catheter cannot be used to insert directly into the ascending aorta in the vicinity of the heart to obstruct the blood flow. Particularly, since the direction of inserting the occlusion catheter is opposite to the direction when the occlusion catheter is inserted through the femoral aorta, a new problem is caused that the cardiac muscle protective drug, which is released from the distal end, flows toward the lower limbs instead of being delivered to the coronary artery.
The inventors therefore completed the occlusion catheter of the present invention to also solve the new problem.
The occlusion catheter of the present invention comprises: a catheter tube having at least a first lumen and a second lumen independent of each other; and a balloon provided on the outer circumference of the distal end of the catheter tube for being inflated/deflated in accordance with supply or drainage of the fluid through the first lumen in order to obstruct the blood flow within the ascending aorta when inflated, the catheter tube being provided with a drug release aperture for releasing a drug supplied through the second lumen in the position closer to the proximal end than the site where the blood flow is obstructed by the balloon on the outer circumference of the distal end of the catheter tube.
The present occlusion catheter, even when it is inserted directly into the ascending aorta in the vicinity of the heart to obstruct the blood flow, enables delivery of a drug such as a cardiac muscle protective drug to the vicinity of the coronary ostium by supplying the drug through the second lumen.
Further, since the occlusion catheter is inserted directly into the ascending aorta in the vicinity of the heart instead of being inserted through the femoral artery in the conventional manner, the blood flow toward the lower limbs is not prevented, and the flow rate of the drug such as the cardiac muscle protective drug can easily be increased. Also, calcification or meandering of the blood vessel in the lower limb or the aorta does not present problems at the insertion of the catheter.
In another aspect of the present invention, the occlusion catheter comprises: a catheter tube having at least a first lumen and a second lumen independent of each other; and a balloon provided on the outer circumference of the distal end of the catheter tube for being inflated/deflated in accordance with supply or drainage of the fluid through the first lumen to obstruct the blood flow within the ascending aorta when inflated, the balloon having a configuration with a concavity on the outer surface at least when inflated and being joined to the catheter tube in the concavity, the catheter tube being provided with a side aperture for communicating the outside of the catheter tube and the second lumen in the different position from a concavity of the balloon, and the side aperture enabling release of a drug therefrom by supplying the drug through the second lumen.
The concavity is a region in which the balloon sinks toward its inside and also is joined to the catheter tube. The concavity may be previously formed at the time of forming the balloon or may be formed as the result of the balloon, which is made of a substantially elastic material, expanding in the axial direction of the catheter tube when inflated. With such a concavity, in the case where the catheter tube is slightly displaced in the axial direction, the concavity is deformed to expand toward the outside of the balloon in accordance with the displacement of the catheter tube and without having the balloon displaced. Thus, the balloon can easily be retained in the proper indwelling position without being displaced.
In a further aspect of the present invention, the occlusion catheter comprises: a catheter tube having at least a first lumen and a second lumen independent of each other; and a balloon provided on the outer circumference of the distal end of the catheter tube for being inflated/deflated in accordance with supply or drainage of the fluid through the first lumen to obstruct the blood flow within the ascending aorta when inflated, the balloon having a configuration with a depression in a part of the center of the balloon at least when inflated and being joined to said catheter tube in the depression, and the catheter tube being provided with a side aperture in the side wall in the depression of the balloon, for communicating the outside of the catheter tube and the second lumen to enable release of a drug from the side aperture by supplying the drug through the second lumen.
With the structure as above, when the occlusion catheter is inserted approximately perpendicular to a blood vessel, the balloon is supported by the blood vessel wall symmetrically relative to the catheter tube, and is retained in the proper indwelling position within the blood vessel. Thus, the balloon is not displaced by the blood flow from a pump oxygenator or the injection pressure of the cardiac muscle protective drug, and therefore the tube is not required to have an excessive rigidity. Also, this structure allows the balloon to be relatively small while keeping the same advantage as described above.
The above described occlusion catheter preferably has a portion, from the distal end of the catheter tube to the position a predetermined distance away from the distal end, which is reinforced by a reinforcement member. This improves the position retainability of the occlusion catheter.
In another aspect of the present invention, an occlusion catheter for the ascending aorta comprises: a catheter tube having two or more lumens, including at least a first lumen and a second lumen formed therewithin; a balloon provided on the outer circumference of the distal end of the catheter tube for being inflated/deflated in accordance with supply or drainage of the fluid through the first lumen in order to obstruct the blood flow within the ascending aorta when inflated, the catheter tube being provided with a side aperture in the position closer to the proximal end than the balloon, for communicating the outside of the catheter tube and the second lumen to enable release of a drug from the side aperture by supplying the drug through the second lumen; and a valve provided within the second lumen having a structure capable of passing a guide wire therethrough and shutting the fluid flow at least when the guide wire is not passed.
In the occlusion catheter having such a structure, the valve provided inside the second lumen allows the guide wire to pass through the valve, and the second lumen may be used as a guide wire insertion lumen.
Moreover, the valve prevents the blood in the blood vessel from flowing into the second lumen through an opening provided at the distal tip end (hereinafter referred to as xe2x80x9ca distal end openingxe2x80x9d) of the catheter tube, while, at the same time, preventing the fluid in the second lumen from flowing out into the blood vessel. Therefore, the second lumen may be used for purposes other than guide wire insertion.
In the occlusion catheter as above, the guide wire is passed through a short section from the distal end opening to the side aperture of the catheter tube. Accordingly, when the guide wire is placed in a patient""s body and a portion of the guide wire exposed to the outside of the body is relatively short, the portion can be passed through the section from the distal end opening to the side aperture of the catheter tube. Therefore, compared with a catheter having a guide wire insertion lumen throughout the length of the catheter, there is no need of using an excessively long guide wire or connecting another guide wire for extension to the guide wire.